The present invention relates to a position measuring system for a hydraulic cylinder, in which at least one sensor for detecting magnetic fields recognizes a pattern provided on a piston rod of the hydraulic cylinder and thus determines the position of the piston.
Position measuring systems for hydraulic cylinders are used wherever the control or regulation of the length of stroke requires a precise knowledge of the position of the piston.
From EP 0 618 373 B1 a position measuring system is known, in which the piston rod is provided with a groove structure and this structure is scanned magnetically. There are used very deep structures, which are filled up with a ceramic coating. Such ceramic coatings are very hard, but have the disadvantage that the sharp-edged ceramic grains abrasively damage the sealing system of the hydraulic cylinder. Thus, a system with a ceramic coating is not suitable for applications with many cylinder strokes and is limited in its useful life.